Incorporation of Gutter Layers in Polyamide Thin Film Composite Membranes By Electrospray 3D Printing

Martina Jagielski^1,2, Mert Can Hacifazlioglu^1,2, Jeffrey McCutcheon^1,2*

¹Department of Chemical & Biomolecular Engineering, Center for Environmental Sciences and Engineering, University of Connecticut, Storrs, CT, United States, 06269

²Connecticut Center for Applied Separations Technology, University of Connecticut, Storrs, CT,

United States, 06269

*jeffrey.mccutcheon@uconn.edu

ABSTRACT

Polyamide membranes are very prevalent in the membrane desalination field and are applied to nanofiltration (NF) and reverse osmosis (RO) membranes. The successful commercialization and application of these membranes is due to Interfacial Polymerization (IP), which is a reaction between a diamine and an acid chloride. This process forms a thin and densely cross-linked layer on a porous substrate. These membranes have competitive selectivities and much higher water permeances compared to their predecessors (Loeb-Sourirajan membranes). However, the IP process cannot control thickness and chemistries directly, and relies heavily on the support membrane for the characteristics and limitations of the membrane. This support dependence is one of the biggest issues for water transport, since supports, especially those of lower porosity, disrupt the diffusive flow of water and restrict membranes’ permeance. Historically, gutter layers have been utilized in gas separation to address this issue of support dependence, but they are unprecedented in desalination. A gutter layer is a thin layer between the support substrate and the selective layer which acts as a barrier between the two to lessen water’s disruptive flow. It creates a shorter and less resistant transport path for water and stops pore blockage, which would solve the issue of support dependence. IP is not a compatible process for forming gutter layers but electrospray 3D printing offers more possibilities. This method utilizes an electric field to atomize solvent droplets that are sprayed on the substrate and react directly at the surface to form membrane structures. This method provides the possibility to make gutter layers with varying and controllable thickness using different monomers. In this work, we focus on the creation of tunable gutter layers to see whether they can increase the permeances of RO and NF membranes. Improvement in membrane performance via gutter layers would advance future membrane-based desalination technologies, allowing for routes such as customizable membranes and broadening current niche purposes in the market.